Choosing the Right Drill Bit for 0.8 mm Vias: A Practical Guide for Hobbyist PCB Makers

If you’ve ever tried to drill a 0.8 mm via and ended up with a ragged hole or a broken tip, you know the frustration. In today’s flood of cheap PCB services, many makers still love to spin their own boards. Getting that tiny hole clean and round is the difference between a board that works and one that sits in a drawer forever. Below is the step‑by‑step approach I use at Precision Drilling Hub, written in plain language so you can start drilling like a pro right away.

Why 0.8 mm Vias Matter

Most hobbyist designs use 0.8 mm as the standard via size because it balances current capacity and board density. It’s small enough to keep the board thin, yet large enough to handle a decent amount of current for Arduino‑level projects. If the hole is too big, you waste copper and risk misalignment with the component pads. If it’s too small or out of round, the plating process can miss spots, leading to intermittent connections.

The Anatomy of a Micro Drill Bit

Material: Carbide vs. High‑Speed Steel

Carbide bits are the workhorse for sub‑millimeter drilling. They stay sharp longer, resist heat, and give a cleaner cut. High‑speed steel (HSS) is cheaper, but it dulls fast at the speeds we need for 0.8 mm holes. My rule of thumb: if you plan to drill more than ten boards a month, spend the extra few dollars on carbide.

Point Angle

The point angle is the angle formed at the tip of the bit. For tiny holes, a 118‑degree angle is common because it gives a sharp point without being too fragile. Some makers swear by 135‑degree bits for extra rigidity, but I’ve found they tend to wander a bit on thin copper.

Flute Length and Pitch

Flutes are the grooves that carry chips away from the hole. A short flute (about 1 mm) works well for PCB material because the chips are tiny and the bit doesn’t need a long channel. Pitch, the distance between flutes, should be fine – usually two flutes are enough for 0.8 mm bits.

Shank Size

Most micro bits come with a 1 mm or 2 mm shank. The shank must match your drill chuck. I use a 2 mm shank on my bench‑top PCB drill press because it gives a more stable grip and reduces wobble. If you only have a rotary tool, a 1 mm shank with a collet works fine, but expect a little more chatter.

Setting Up Your Drill

Speed (RPM)

Higher speeds reduce the force needed to cut, which helps keep the bit from breaking. For a 0.8 mm carbide bit, aim for 30 000 to 35 000 RPM. My little drill press can hit 38 000, so I dial it back a notch to avoid overheating.

Feed Rate

Feed rate is how fast you push the bit into the board. A slow, steady feed is key. I usually set the feed to about 0.1 mm per second. If you push faster, you’ll generate heat and chip buildup, which leads to a ragged hole.

Lubrication

A drop of cutting oil or even a little water can keep the bit cool and flush chips out. I prefer a light mineral oil because it evaporates quickly and doesn’t leave residue on the copper.

My Personal Drill‑Down Story

The first time I tried a 0.8 mm via on a home‑brew board, I used a cheap HSS bit I found in a hardware store. The bit snapped after the third hole, and the board looked like a Swiss cheese. I spent an afternoon cleaning up the mess and still had to re‑drill the whole batch. That experience taught me two things: never skimp on the bit material, and always check the bit’s runout (the wobble) before you start. After that, I upgraded to a set of 0.8 mm carbide bits from a reputable supplier, and the difference was night and day. The holes were clean, round, and required no touch‑up.

Choosing the Right Bit for Your Project

Below is a quick decision matrix I keep on my workbench:

Low volume, occasional use – 0.8 mm HSS with a 1 mm shank. Good for a single prototype, but expect to replace it often.
Medium volume, hobbyist batch runs – 0.8 mm carbide, 2 mm shank. Provides a good balance of cost and durability.
High precision, tight tolerances – 0.7 mm carbide for a slightly tighter hole, or a 0.9 mm bit if you want a little extra clearance for hand‑soldered vias.

Remember, the bit size you choose should match the copper thickness and the plating process you plan to use. If you’re sending the board out for professional plating, ask the fab if they have a preferred drill size.

Maintenance Tips to Extend Bit Life

Inspect before each session – Look for chips stuck in the flutes and clean them with a soft brush.
Check runout – Spin the bit at low speed and watch the tip. Any wobble means the bit is bent and should be replaced.
Store properly – Keep bits in a small metal case with a soft liner. Moisture can cause rust on HSS bits, and carbide can pick up grit if left loose.

Final Thoughts

Drilling 0.8 mm vias isn’t rocket science, but it does demand a bit of respect for the tiny tools you’re using. By picking the right material, matching the shank to your drill, and dialing in speed and feed, you’ll get clean holes that make your boards look professional. At Precision Drilling Hub we’ve tried every cheap bit on the market, and the verdict is clear: invest in a good carbide set and treat the bits like delicate brushes, not chisels. Your future self will thank you when the next batch of boards comes out perfect on the first try.